Many efforts have been made to develop improved ways of handling cattle excrement and waste water from the cleaning of cattle and preparing them for milking. While such material has some value as fertilizer, modern farming methods rely much more heavily upon chemical fertilizers to provide carefully balanced soil nutriments; and the animal wastes are spread on the fields principally as a means of distributing them where they can leach into the soil and be of some additional benefit.
Agricultural authorities have recognized for some time that ruminant animal feces contain substantial amounts of undigested fibrous material which is preponderantly short pieces that consist of bundles of capillary tubes. The undigested fibrous material has little value for soil building purposes, and in recent years several efforts have been made to separate it from the remaining waste material and recover it in a useable form. Conversely, except for the liquid in and around the capillary tubes of the fibrous material, practically all of the valuable soil improving chemicals in the animal waste are not in the undigested fibrous material. The fibrous material is coarse enough that it makes the natural animal waste very difficult to handle with anything but mechanical spreaders; whereas, if the fibrous material can be separated from the liquids and finer solids, the latter can be handled by an ordinary slurry pump which distributes it like liquid fertilizer.